The present invention relates to an improved apparatus utilizing the effect caused by the passage of a continuous air flow through a relatively large number of electrically heated small diameter ducts in which energy is dissipated by the Joule effect and wherein the high thermal gradient as produced in the interior of the ducts exhibits an average value of 220.degree. C. such that the protein membrane associated with most bacteria and virus found in the air is destroyed.
The concept of employing thermal effect as a sterilizing agent is generally well known, as is also the idea that the Joule effect may be used as a heating source. Examples of prior devices for cleaning or purifying air by means of an elongated or tubular passageway associated with heating means will be found in U.S. Pat. Nos. 2,014,455, 2,564,898 and 3,691,346. Such devices either require the consumption of a relatively high amount of current, emit a concentrated air flow and/or result in the discharge of air at a noticeably elevated temperature. Until the instant invention, thermal processes for obtaining air sterilization, without using electrostatic or catalytic devices, have resulted in the significant heating of the ambient air.
Presently, several methods are employed to achieve air sterilization in situations where the proliferation of micro-organisms is high. The most common methods include the direct use of Joule effect by simple heating or by incandescent bulbs. This does not present any improvement of a thermodynamic nature and thus exhibits low efficiency as far as the sterilization effect is concerned. An additional method has been the use of ultra-violet radiation in forced air-flow chambers.